This project examines the kinetics of melatonin in relation to human puberty in normal individuals ages 6-30 years, and in children with delayed puberty. Serum, saliva and urine samples are collected at baseline and at frequent intervals after an intravenous infusion of melatonin for determination of concentrations of melatonin and its metabolite, 6-sulfatoxymelatonin. Kinetic parameters are calculated for each subject and comparisons of results are performed by pubertal groups. A preliminary pilot test was performed in 3 healthy adults, using 3 different doses of melatonin to determine a suitable test dose. Data analysis is currently underway on results of 33 subjects.